1. Field of the Invention
This invention relates to network interfaces, more specifically, those network interfaces that use the Simple Network Management Protocol (SNMP).
2. Background of the Invention
The Simple Network Management Protocol (SNMP) was originally developed in 1988 for internetwork management. One of its main goals was to provide a simple design that would facilitate its widespread and rapid deployment. SNMP has several other advantages, among those is the separation between the management architecture and the hardware device architectures. This allows for a much wider base of supported devices.
Network management systems such as SNMP typically have two primary elements, a manager and agents. Managers are also referred to as applications. These managers contain software that runs on a network management station, such as a PC or workstation. The manager software implements the protocols used to exchange data with the network agents. The managers send out queries to gather information about the status, configuration and performance, as well as other parameters of external devices.
The external devices, sometimes referred to as network components. The network components contain the agents that receive to the queries from the manager, gather the necessary information and respond to the manager. The agent is a software element. These queries and responses allow the network administrator to access and manage objects in the network.
In SNMP, the messages have a predefined format called a protocol data unit, or PDU. There are five different types of message sent in the PDU format. The manager issues three types of messages to retrieve object variables: GetRequest messages, GetNextRequest messages, and SetRequest messages. The agent acknowledges all three types of messages with a GetResponse message, which passes back to the manager. A fifth type of message is called a trap, in which the agent notifies the manager of some type of error condition, such as a value that exceeds a predefined threshold.
Problems can occur if the format of the message is somehow corrupted or inaccurate. For example, if the manager sending the agent does not send a complete PDU, the agent does not know how to respond. Currently, no practical method exists to adapt to problems caused by incomplete PDUs. Therefore, a method is needed that corrects this problem and allows the network to continue to function.
One aspect of the invention is a method of reconstructing a partial network agent message. The method involves receiving a partial network agent message from a network interface, rebuilding the message and sending the rebuilt message to a network agent. In one embodiment of the invention, the partial network agent message is a protocol data unit under the simple network management protocol (SNMP). In alternative embodiments of the invention, the network is designed with knowledge that the network agent message is incomplete, or the incomplete message is detected during network operation.